**Core Concept**
Somnambulism, also known as sleepwalking, is a parasomnia disorder characterized by complex behaviors performed during deep non-rapid eye movement (NREM) sleep. It is often associated with sleep stage transitions and can be triggered by sleep deprivation, stress, or certain medications.

**Why the Correct Answer is Right**
Somnambulism typically occurs during the slow-wave sleep stage of NREM sleep, which is characterized by slow delta waves and low arousal thresholds. Individuals with somnambulism often have difficulty recalling their nighttime activities due to the amnestic properties of sleep. The brain regions involved in somnambulism include the hippocampus, amygdala, and prefrontal cortex, which regulate emotion, memory, and executive function.

**Why Each Wrong Option is Incorrect**
**Option A:** Somnambulism can indeed occur in association with sleep stage transitions, such as during arousals from slow-wave sleep. This is often observed in individuals with a history of sleepwalking.
**Option B:** Sleep deprivation is a well-established risk factor for somnambulism, as it can disrupt normal sleep-wake cycles and increase the likelihood of sleep stage transitions.
**Option C:** Certain medications, such as sedatives and antidepressants, can trigger somnambulism by altering normal sleep patterns and increasing the risk of sleep stage transitions.

**Clinical Pearl / High-Yield Fact**
Somnambulism can be a precursor to other sleep-related disorders, such as sleep terrors and REM sleep behavior disorder. It is essential to address underlying sleep disorders and modifiable risk factors, such as sleep deprivation and stress, to prevent the recurrence of somnambulism.

**Correct Answer: D**